THE MONTHLY BULLETIN. 



483 



ENTOMOLOGICAL. 



A LITTLE KNOWN ORCHID PEST. 



{Isosoma orchidearum West.) 



Order 



Family — Eurytomidae. 

 "Whitney. 



-Hymenoptera. 

 By L. A. 



Some time ago the writer's attention was called to a small hymenop- 

 terous insect attacking orchids at a local greenhouse. A number of 

 larvae and pupae were secured and on the emergence of the adults speci- 

 mens were forwarded to Washington, D. C, where they were identified 

 through the kindness of Mr. J. C. Crawford as the orchid Isosoma 

 {Isosoma orchidearum) . 



This insect is popularly known to gardeners and florists as the Catt- 

 leya fly. as it confines its attacks solely to the family of orchids and is 



Fig. 111. — Distorted orchid bulb, resulting from infestation by Isosoma orchidearum. 



(Original.) 



without doubt one of the worst insect pests to which the plant is subject. 

 Very little literature pertaining to this insect is available, the principal 

 notes being in Insect Life.^ 



This insect belongs to the family Eurytomidse, a group of insects that 

 is normally parasitic. Entomologists refused to credit them with 

 phytophagic habits for years, and the fact was established only after 

 extensive experiments. 



Other species of this genus are some of the worst pests of grains and 

 grasses that we have, being commonly known as the grass joint worms. 

 Prof. Webster of the United States Department of Agriculture gives 



^Insect Life, Vol. I, page 121 ; Vol. II, pages 250-251. 



